Ultrasonic energy had been used to enhance the intravascular delivery and/or effect of various therapeutic compounds. In one system, ultrasound catheters are used to deliver ultrasonic energy and therapeutic compounds to a treatment site within a patient's vasculature. Such ultrasound catheters can comprise an elongate member configured to be advanced through a patient's vasculature and an ultrasound assembly that is positioned near a distal end portion of the elongate member. The ultrasound assembly is configured to emit ultrasonic energy. Such ultrasound catheters can include a fluid delivery lumen that is used to deliver the therapeutic compound to the treatment site. In this manner, ultrasonic energy is delivered to the treatment site to enhance the effect and/or delivery of the therapeutic compound.
For example, ultrasound catheters have been successfully used to treat human blood vessels that have become occluded by plaque, thrombi, emboli or other substances that reduce the blood carrying capacity of the vessel. See, for example, U.S. Pat. No. 6,001,069. To remove the occlusion, the ultrasound catheter is advanced through the patient's vasculature to deliver a therapeutic compound containing dissolution compounds directly to the occlusion. To enhance the effect and/or delivery of the therapeutic compound, ultrasonic energy is emitted into the therapeutic compound and/or the surrounding tissue at the treatment site. In other applications, ultrasound catheters are used for other purposes, such as for the delivery and activation of light activated drugs. See, for example, U.S. Pat. No. 6,176,842.